Diisobutylammonium triphenyl(2-thiolatoacetato-κ2O,S)stannate(IV)

The title salt features a distorted cis-trigonal-bipyramid coordination geometry around the tin atom.

Crystals of the title salt, (C 8 H 20 N)[Sn(C 6 H 5 ) 3 (C 2 H 2 O 2 S)], comprise diisobutylammonium cations and mercaptoacetatotriphenylstannate(IV) anions.The bidentate binding mode of the mercaptoacetate ligand gives rise to a five-coordinated, ionic triphenyltin complex with a distorted cis-trigonalbipyramidal geometry around the tin atom.In the crystal, charge-assisted ammonium-N-H� � �O(carboxylate) hydrogen-bonding connects two cations and two anions into a four-ion aggregate.Two positions were resolved for one of the phenyl rings with the major component having a site occupancy factor of 0.60 (3).

Structure description
One of the authors has reported some ionic di-and triorganotin complexes (Song et al., 2005(Song et al., , 2005;;Zhong et al., 2005) as part of efforts to modify structures of organotin complexes with the aim to increase their aqueous solubility (Gielen, 2002).The title salt is another example of an ionic triphenyltin complex of mercaptoacetic acid.The salt comprises a diisobutylammonium cation and a mercaptoacetatotriphenylstannate anion, Fig. 1.This new species is similar to other reported ionic complexes like di-cyclohexylammonium thiolactatotriphenylstannate (Song et al., 2006), trimethylammonium chloridodiphenylmercaptoacetatostannnate (Song et al., 2005) and 2-methylpyrimidium chloridodiphenylmercaptostannate (Zhong et al., 2005).In the new salt, the Ph 3 Sn residue is covalently bound to a sulfur atom (Sn1-S1 2.423 (1) A ˚) and also to a less tightly bound carboxylate-O atom as indicated by the relatively long Sn1-O1 bond length of 2.456 (2) A ˚.The coordination environment around the Sn atom is based on a distorted cis-trigonal-bipyramidal geometry with the O1 and C3 atoms in the axial positions, and the S1, C9 and C15 atoms in the equatorial plane.The axial axis is bent with the C3-Sn1-O1 angle being 168.74 (10) � .The S1-Sn1-O1 angle is significantly reduced [75.58(6) � ] from 90 � due to the restricted bite distance of the mercaptoacetato ligand.
Charge-assisted hydrogen-bonding interactions (Table 1) between the di-iso-butylammonium cations and the mercaptoacetatotriphenylstannate anions are observed in the crystal.As shown in Fig. 2, one ammonium-N-H atom forms a hydrogen bond to the carbonyl-O atom of one carboxylate residue and the second ammonium-N-H atom bifurcates the carboxyl-O atom of a centrosymmetrically related carboxylate residue.In this way, a four-ion aggregate is formed with a central twelve-membered {� � �HNH� � �OCO} 2 synthon with the outer N-H� � �O hydrogen bonds lying above and below the encompassed eight-membered {� � �HNH� � �O} 2 synthon.The hydrogen bonding substantially affects the distribution of the electrons within the carboxylate group, which can be seen by the observation of experimentally equivalent C-O bond lengths, i.e. 1.238 (4) A ˚for the C1-O1 bond and 1.241 (4) A for the C1-O2 bond.

Figure 1
The molecular structures of the two ions comprising the asymmetric unit in the title salt showing the atom-labelling scheme and anisotropic displacement ellipsoids at the 50% probability level.

Refinement
Crystal data, data collection and structure refinement details are summarized in

Special details
Geometry.All esds (except the esd in the dihedral angle between two l.s.planes) are estimated using the full covariance matrix.The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry.An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s.planes.

Figure 2 A
Figure 2 A view of the four-ion aggregate in the crystal of the title salt.Dashed lines indicate hydrogen bonds.

Table 2
Experimental details.